// pvtutorial03.c
// A pedagogical video player that will stream through every video frame as fast as it can
// and play audio (out of sync).
//
// Code based on FFplay, Copyright (c) 2003 Fabrice Bellard, 
// and a tutorial by Martin Bohme (boehme@inb.uni-luebeckREMOVETHIS.de)
// Tested on Gentoo, CVS version 5/01/07 compiled with GCC 4.1.1
// Use
//
// gcc -g -I/usr/local/include -L/usr/local/lib -o pvtutorial03 pvtutorial03.c -lavutil -lavformat -lavcodec -lswscale -lz -lm `sdl-config --cflags --libs`
// to build (assuming libavformat and libavcodec are correctly installed, 
// and assuming you have sdl-config. Please refer to SDL docs for your installation.)
//
// Run using
// pvtutorial03 myvideofile.mpg
//
// to play the stream on your screen.


#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>

#include <SDL.h>
#include <SDL_thread.h>

#include <stdio.h>

#define SDL_AUDIO_BUFFER_SIZE 1024

typedef struct PacketQueue {
  AVPacketList *first_pkt, *last_pkt;
  int nb_packets;
  int size;
  SDL_mutex *mutex;
  SDL_cond *cond;
} PacketQueue;

PacketQueue audioq;

static int quit = 0;
static uint8_t *audio_buf = NULL;
static uint8_t silence_buf[SDL_AUDIO_BUFFER_SIZE];

void packet_queue_init(PacketQueue *q) 
{
  memset(q, 0, sizeof(PacketQueue));
  q->mutex = SDL_CreateMutex();
  q->cond = SDL_CreateCond();
}

int packet_queue_put(PacketQueue *q, AVPacket *pkt) 
{
  AVPacketList *pkt1;
 
  //printf("Audio pkt enque size(%d).\n", q->size);

  if(av_dup_packet(pkt) < 0)
    return -1;
  
  pkt1 = av_malloc(sizeof(AVPacketList));
  if (!pkt1)
    return -1;
  pkt1->pkt = *pkt;
  pkt1->next = NULL;
  
  
  SDL_LockMutex(q->mutex);
  
  if (!q->last_pkt)
    q->first_pkt = pkt1;
  else
    q->last_pkt->next = pkt1;

  q->last_pkt = pkt1;
  q->nb_packets++;
  q->size += pkt1->pkt.size;

  SDL_CondSignal(q->cond);  
  SDL_UnlockMutex(q->mutex);

  return 0;
}

static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block)
{
  AVPacketList *pkt1;
  int ret;
 
  //printf("Aduio pkt deque size(%d).\n", q->size); 
  SDL_LockMutex(q->mutex);
  
  for(;;) {
    
    if(quit) {
      ret = -1;
      break;
    }

    pkt1 = q->first_pkt;
    if (pkt1) {
      q->first_pkt = pkt1->next;
      if (!q->first_pkt)
	q->last_pkt = NULL;
      q->nb_packets--;
      q->size -= pkt1->pkt.size;
      *pkt = pkt1->pkt;
      av_free(pkt1);
      ret = 1;
      break;
    } else if (!block) {
      ret = 0;
      break;
    } else {
      SDL_CondWait(q->cond, q->mutex);
    }
  }

  SDL_UnlockMutex(q->mutex);

  return ret;
}

int audio_decode_frame(AVCodecContext *aCodecCtx)
{
  static AVPacket pkt, pkt_temp, flush_pkt;
  static AVFrame*  pfrm = NULL;

  int got_frame;
  int new_packet = 0;
  int flush_complete = 0;
  int len1, len2, data_size, resampled_data_size;
  int wanted_nb_samples;
  int64_t dec_channel_layout;

  if(!pfrm) 
    if(!(pfrm = avcodec_alloc_frame())) { /**< memory leak!!! */
       return AVERROR(ENOMEM);
    }

  for(;;) {
    while(pkt_temp.size > 0 || (!pkt_temp.data && new_packet > 0)) {
      if (flush_complete)
        break;
      new_packet = 0;
      len1 = avcodec_decode_audio4(aCodecCtx, pfrm, &got_frame, &pkt_temp);
      if(len1 < 0) {
	/* if error, skip frame */
	pkt_temp.size = 0;
	break;
      }
      pkt_temp.data += len1;
      pkt_temp.size -= len1;
      if (!got_frame) {
	if(!pkt_temp.data && aCodecCtx->codec->capabilities & CODEC_CAP_DELAY)
          flush_complete = 1;
        continue;
      }

      data_size = av_samples_get_buffer_size(NULL, aCodecCtx->channels, pfrm->nb_samples, aCodecCtx->sample_fmt, 1);

      audio_buf = pfrm->data[0];	/**< store decoded audio sample data to global variable*/
      if(data_size <= 0) {
	/* No data yet, get more frames */
	continue;
      }
      /* We have data, return it and come back for more later */
      return data_size;
    }

    if(pkt.data)
      av_free_packet(&pkt);
    memset(&pkt_temp, 0, sizeof(pkt_temp));    

    if(quit)
      return -1;

    if( (new_packet = packet_queue_get(&audioq, &pkt, 1)) < 0)
      return -1;

    if(pkt.data == flush_pkt.data) {
      avcodec_flush_buffers(aCodecCtx);
      flush_complete = 0;
    }
    pkt_temp = pkt;
  }

}


void audio_callback(void *userdata, Uint8 *stream, int len)
{
  AVCodecContext *aCodecCtx = (AVCodecContext *)userdata;
  int len1, audio_size;
  int bytes_per_sec;
  int frame_size = av_samples_get_buffer_size(NULL, aCodecCtx->channels, 1, aCodecCtx->sample_fmt, 1);

  static unsigned int audio_buf_size;
  static unsigned int audio_buf_index;

  //printf("audio_callback time(%ld)\n", clock());
  while(len > 0) {
    if(audio_buf_index >= audio_buf_size) {
      /* We have already sent all our data; get more */
      audio_size = audio_decode_frame(aCodecCtx);
      if(audio_size < 0) {
	/* If error, output silence */
	audio_buf = silence_buf;
	audio_buf_size = sizeof(silence_buf) / frame_size * frame_size;
      } else {
	audio_buf_size = audio_size;
      }

      audio_buf_index = 0;
    }

    len1 = audio_buf_size - audio_buf_index;

    if(len1 > len)
      len1 = len;

    memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);
    len -= len1;
    stream += len1;
    audio_buf_index += len1;
  }
}

int main(int argc, char *argv[]) 
{
  int             i, videoStream, audioStream;
  int             frameFinished;
  float           aspect_ratio;
 
  struct SwsContext *img_convert_ctx = NULL;

  AVFormatContext *pFormatCtx = NULL;
  AVCodecContext  *pCodecCtx = NULL;
  AVCodecContext  *aCodecCtx = NULL;

  AVCodec         *pCodec = NULL;
  AVCodec         *aCodec = NULL;

  AVFrame         *pFrame = NULL; 
  AVPacket        packet;

  SDL_Overlay     *bmp = NULL;
  SDL_Surface     *screen;
  SDL_Rect        rect;
  SDL_Event       event;
  SDL_AudioSpec   wanted_spec, spec;

  if(argc < 2) {
    fprintf(stderr, "Usage: test <file>\n");
    exit(1);
  }

  // Register all formats and codecs
  av_register_all();
  
  if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
    fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
    exit(1);
  }

  // Open video file
  if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL) != 0)
    return -1; // Couldn't open file
  
  // Retrieve stream information
  if(avformat_find_stream_info(pFormatCtx, NULL) < 0)
    return -1; // Couldn't find stream information
  
  // Dump information about file onto standard error
  av_dump_format(pFormatCtx, 0, argv[1], 0);
  
  // Find the first video stream
  videoStream = -1;
  audioStream = -1;
  for(i = 0; i < pFormatCtx->nb_streams; i++) {
    if(pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO &&
       videoStream < 0) {
      videoStream = i;
    }
    if(pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO &&
       audioStream < 0) {
      audioStream = i;
    }
  }

  if(videoStream == -1)
    return -1; // Didn't find a video stream
  if(audioStream == -1)
    return -1;
   
  aCodecCtx=pFormatCtx->streams[audioStream]->codec;
  // Set audio settings from codec info
  wanted_spec.freq = aCodecCtx->sample_rate;
  wanted_spec.format = AUDIO_S16SYS;
  wanted_spec.channels = aCodecCtx->channels;
  wanted_spec.silence = 0;
  wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
  wanted_spec.callback = audio_callback;
  wanted_spec.userdata = aCodecCtx;
  
  if(SDL_OpenAudio(&wanted_spec, &spec) < 0) {
    fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
    return -1;
  }

  aCodec = avcodec_find_decoder(aCodecCtx->codec_id);
  if(!aCodec) {
    fprintf(stderr, "Unsupported codec!\n");
    return -1;
  }
  // Open audio codec
  if(avcodec_open2(aCodecCtx, aCodec, NULL) < 0)
    return -1;

  // audio_st = pFormatCtx->streams[index]
  packet_queue_init(&audioq);
  SDL_PauseAudio(0);

  // Get a pointer to the codec context for the video stream
  pCodecCtx=pFormatCtx->streams[videoStream]->codec;
  
  // Find the decoder for the video stream
  pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
  if(pCodec == NULL) {
    fprintf(stderr, "Unsupported codec!\n");
    return -1; // Codec not found
  }

  // Open video codec
  if(avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
    return -1; // Could not open codec
  
  // Allocate video frame
  pFrame = avcodec_alloc_frame();

  // Make a screen to put our video

#ifndef __DARWIN__
        screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);
#else
        screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 24, 0);
#endif
  if(!screen) {
    fprintf(stderr, "SDL: could not set video mode - exiting\n");
    exit(1);
  }
  
  // Allocate a place to put our YUV image on that screen
  bmp = SDL_CreateYUVOverlay(pCodecCtx->width,
				 pCodecCtx->height,
				 SDL_YV12_OVERLAY,
				 screen);


  img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height,
 	pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height,
	PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);

  while(av_read_frame(pFormatCtx, &packet)>=0) {
    // Is this a packet from the video stream?
    if(packet.stream_index == videoStream) {
      // Decode video frame
      avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, 
			   &packet);
      
      // Did we get a video frame?
      if(frameFinished) {
	SDL_LockYUVOverlay(bmp);

	AVPicture pict;
	pict.data[0] = bmp->pixels[0];
	pict.data[1] = bmp->pixels[2];
	pict.data[2] = bmp->pixels[1];

	pict.linesize[0] = bmp->pitches[0];
	pict.linesize[1] = bmp->pitches[2];
	pict.linesize[2] = bmp->pitches[1];

	// Convert the image into YUV format that SDL uses
	sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, 
		pFrame->linesize, 0, pCodecCtx->height, pict.data, pict.linesize);
	
	SDL_UnlockYUVOverlay(bmp);
	
	rect.x = 0;
	rect.y = 0;
	rect.w = pCodecCtx->width;
	rect.h = pCodecCtx->height;
	SDL_DisplayYUVOverlay(bmp, &rect);
        SDL_Delay(20);
	av_free_packet(&packet);
      }
    } else if(packet.stream_index == audioStream) {
	//printf("audioStream packet_queue_put.\n");
      packet_queue_put(&audioq, &packet);
    } else {
      av_free_packet(&packet);
    }
    // Free the packet that was allocated by av_read_frame
    SDL_PollEvent(&event);
    switch(event.type) {
    case SDL_QUIT:
      quit = 1;
      SDL_Quit();
      exit(0);
      break;
    default:
      break;
    }

  }

  //
  SDL_FreeYUVOverlay(bmp);
  SDL_FreeSurface(screen);
  //SDL_Quit();

  // 
  sws_freeContext(img_convert_ctx);

  // Free the YUV frame
  av_free(pFrame);
  
  // Close the codec
  avcodec_close(pCodecCtx);
  
  // Close the video file
  avformat_close_input(&pFormatCtx);
  
  return 0;
}
